Touchscreens
A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touching the display of the device with a finger or hand. Touchscreens can also sense other passive objects, such as a stylus. Touchscreens are common in devices such as game consoles, all-in-one computers, tablet computers, and smartphones.
The touchscreen has two main attributes. First, the touchscreen enables one to interact directly with what is displayed, rather than indirectly with a pointer controlled by a mouse or touchpad. Secondly, the touchscreen lets one do so without requiring any intermediate device that would need to be held in the hand (other than a stylus, which is optional for most modern touchscreens). Such displays can be attached to computers, or to networks as terminals. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices, mobile phones, and video games.
Source: http://en.wikipedia.org/wiki/Touchscreen
Capacitive Touchscreens
A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch (e.g., see capacitive sensing touchscreen technology discussed below). The location is then sent to the controller for processing. However, one cannot use a capacitive touchscreen through most types of electrically insulating material, such as gloves, instead one requires a special capacitive stylus, or a special-application glove with an embroidered patch of conductive thread passing through it and contacting the user's fingertip. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones in cold weather.
Source: http://en.wikipedia.org/wiki/Touchscreen
Resistive Touchscreens
Resistive touchscreens are touch-sensitive computer displays composed of two flexible sheets coated with a resistive material and separated by an air gap or microdots. There are two different types of metallic layers. The first type is called Matrix, in which striped electrodes on substrates such as glass or plastic face each other. The second type is called Analogue which consists of transparent electrodes without any patterning facing each other. As of 2011, Analogue offered lowered production costs when compared to Matrix. In Analogue, when contact is made to the surface of the touchscreen, the two sheets are pressed together. On these two sheets there are horizontal and vertical lines that, when pushed together, register the precise location of the touch. Because the touchscreen senses input from contact with nearly any object (finger, stylus/pen, palm) resistive touchscreens are a type of “passive” technology.
For example, during operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the uniform voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur within a few milliseconds, registering the exact touch location as contact is made.
Resistive touchscreens typically have high resolution (4096×4096 DPI or higher), providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device.
Resistive touchscreen technology works well with almost any stylus-like object, and can also be operated with gloved fingers and bare fingers alike. In some circumstances, this is more desirable than a capacitive touchscreen, which has to be operated with a capacitive pointer, such as a bare finger (latest capacitive technology enables gloves on touchscreens). The resistive touchscreen costs are relatively low when compared with active touchscreen technologies. Resistive touchscreen technology can be made to support multi-touch input.
For people who must grip the active portion of the screen or must set their entire hand down on the screen, alternative touchscreen technologies are available, such as an active touchscreen in which only the stylus creates input and skin touches are rejected. However, newer touchscreen technologies allow the use of multi-touch without the aforementioned vectoring issues.
Source: http://en.wikipedia.org/wiki/Resistive_touchscreen
Capacitive Sensing Touchscreen Technology
Source: http://en.wikipedia.org/wiki/Resistive_touchscreen
Capacitive sensing is a technology based on capacitive coupling that is used in many different types of sensors, including those to detect and measure proximity, position or displacement, humidity, fluid level, and acceleration. Capacitive sensing as a human interface device (HID) technology, for example to replace the computer mouse, is growing increasingly popular. Capacitive touch sensors are used in many devices such as laptop trackpads, digital audio players, computer displays, mobile phones, mobile devices, tablets and others. More and more design engineers are selecting capacitive sensors for their versatility, reliability and robustness, unique human-device interface and cost reduction over mechanical switches.
Capacitive sensors detect anything that is conductive or has a dielectric different than that of air. While capacitive sensing applications can replace mechanical buttons with capacitive alternatives, other technologies such as multi-touch and gesture-based touchscreens are also premised on capacitive sensing.
Capacitive sensing touchscreens do not respond to a traditional stylus and instead require a capacitive stylus, which is unable to provide high resolution positional input. A typical capacitive stylus has a conductive tip shaped similar to a fingertip, which is made out of capacitive foam. Another capacitive stylus resembles a ball point pen but has a flat round plastic disk attached to the point of the pen. Still another capacitive stylus has a stainless steel ring that has a vinyl film on the surface that makes contact with a touchscreen. Yet another type of capacitive stylus includes a magnet in the head of the stylus enabling a capacitive sensing touchscreen to detect that it has been touched by the stylus. This stylus is described in U.S. Patent Application No. 2009/0167727, filed Dec. 16, 2008, and entitled “Stylus and Electronic Device”, the contents of which are incorporated herein by reference. FIGS. 1A, 1B, 2A, and 2B (PRIOR ART) are provided from this patent application. FIGS. 1A and 1B depict an electronic device 100 having a device body 110 and a stylus 120. The device body 110 has a capacitive touch panel 112. The stylus 120 has a handle 122 and a head 124. The head 124 is magnetic. The head 124 may be made of a magnetic material or may be provided with a magnet 126 at a tip of the head 124. When a relative speed exists between the head 124 of the stylus 120 and any region of the touch panel 112, an inducing current is generated on the region of the panel 112 due to magnetic force lines M10 of the head 124. FIGS. 2A and 2B (PRIOR ART) depict two distribution modes of magnetic poles of a stylus 120a and 120b. Referring to FIG. 2A, a connection line D10 between magnetic poles N and S of a head 124a of a stylus 120a is substantially perpendicular to a lengthwise direction D20 of a handle 122a.Alternatively, referring to FIG. 2B, a connecting line D30 between magnetic poles N and S of a head 124b of a stylus 120b is substantially parallel to a lengthwise direction D40 of a handle 122b. 
Many devices having capacitive touchscreen interfaces also include at least one vector magnetics sensor (or vector magnetometer) used to determine the orientation of the device or a portion of the device (e.g., a hinged display that can move from an open position to a closed position). More specifically, the at least one magnetics sensor is used to sense (or measure) the magnetic field produced by the Earth and provides one-dimensional, two dimensional, or three-dimensional orientation information in the form of X, Y, and/or Z vector data that can be processed by software typically resident on the device (but which can be remote) to determine how the device is being moved about by the user. Such vector magnetics sensor data (or information) enables applications such as games where the device (e.g., a cell phone) itself can be used as a game controller. Magnetic sensor information can also be used to determine the state of a device's display (e.g., open, closed, nearly closed, etc.), such as is the case with Apple® laptop computers, where the position of the display relative to the keyboard is used to change the state of the machine (e.g., on, sleep, off). Similarly, the cover of the Apple iPad® includes a magnet that is detectable by a magnetic field sensor, which is used for determining whether or not the cover is covering the display. FIG. 3A (PRIOR ART) depicts an exemplary hall sensor array 302 used in a smartphone. FIG. 3B (PRIOR ART) depicts an exemplary cell phone 303 having an exemplary X axis 304, Y axis 306, and Z axis 308. FIG. 3C (PRIOR ART) depicts an exemplary output display showing vector data 310, 312, 314 corresponding to the X, Y, and Z vectors (i.e., magnitude and direction of the X, Y, and Z magnetic field components) as an electronic device such as the cell phone 303 is moved about over a period of time.
Magnets external to a device have been used to interact with an electronic device having a magnetometer. U.S. Patent Application No. 2011/0190060, filed Jan. 31, 2011, and entitled “Around Device Interaction for Controlling and Electronic Device, for Controlling a Computer Game and for User Verification”, the contents of which are incorporated herein by reference, describes use of a magnetometer within an electronic device to measure changes in magnetic strengths resulting from the relative motion of an external magnet in order to identify (or recognize) gesture induced movements. The tracking of the relative movement of a magnet is described as being coarse and magnetic field amplitude based, where polarity is only used to identify one magnet vs. another. The relative motion is only discerned and is not absolute position-based. Generally, gestures can be recognized regardless of where a given motion actually occurs or originates relative to the device. However, because the gestures are position indeterminate the ability to provide high resolution precision input as required for absolute position-based functions such as precision drawing or lettering is not enabled. Instead the coarse movement of the magnet only enables recognition of gestures such as moving a hand downward, swiping left or right, rotating, zooming, etc. Examples of the magnet gesturing systems are provided in FIGS. 4A and 4B (PRIOR ART). FIG. 4A depicts a controlling apparatus 401 comprising a mobile phone 402 and a magnetic ring 403. The mobile phone 402 is held by the left hand 442 and the magnetic ring 403 is on the index finger of the right hand 441. The mobile phone 402 has a touchscreen 421 and a standard magnetic sensor (not shown) that is located inside the mobile phone 402. The mobile phone 402 executes a computer program 422 that implements the controlling means on the phone 402. FIG. 4B depicts a controlling apparatus 410 comprising a stick 430 as the magnetic element.
U.S. Patent Application No. 2012/0084051, filed May 21, 2010, and entitled “Method and Arrangement for Magnetically Determining a Position”, the contents of which are herein incorporated herein by reference, describes magnetically determining a position of a permanent magnet located above a magnetic sensor array, where the vector and local gradient of the magnetic flux density of the a spherical homogenously magnetized magnet is measured using a position sensor. The position and orientation of the magnetic dipole of the permanent magnet relative to the position sensor is calculated from the measured values. A spherical permanent magnet having homogenous magnetization is used to prevent previously present cross-sensitivity between the position and orientation determination, and allowing measurement without prior calibration. FIG. 5 (PRIOR ART) depicts the magnetic field B of a magnetic sphere 501 being tracked by a position sensor 502 comprising an array of Hall Effect sensors 503.
Examples of use of a magnetometer for communicating with an electronic device and determining a position can also be found in a story available on an online blog at http://blog.makezine.com/2012/10/29/magnetic-appcessories-with-andrea-bianchi/, which is incorporated by reference herein in its entirety.
A web log by Joe DesBonnet found at http://jdesbonnet.blogspot.com/2011_05_01_archive.html (the contents of which are incorporated by reference herein) describes a cheap and simple one-way communications link from an Arduino microcontroller to an Android cellphone, where he uses a digital IO line of the Arduino to drive a coil of wire placed over the magnetometer of the Android. He employs a Non Return to Zero encoding scheme, where he monitors the output of one axis (Z) of the magnetometer using the Android ‘Tricorder’ application. He successfully communicated “Hello World!” at approximately 7 bps and suggested potential improvements to increase his data rate including using a DAC, using four power levels to encode 2 bits per symbol and using forward error correction. He also mentions that it might be possible to construct a set of coils that excite the X, Y, and Z channels independently to triple his data rate. He further mentions some applications might only require an analog signal. FIG. 6 (PRIOR ART) depicts the communications link 600 from the Arduino 602 to the Android 604 via the use of a coil 606 placed over the magnetometer (not shown) of the Android 604.